Method for detecting an object via an optical phased array

ABSTRACT

A device for detecting a presence of an object includes an optical phased array, a detector, a processing portion and an indicator. The optical phased array can transmit a first optical beam to a first location at a first time and can transmit a second optical beam to a second location at a second time. The detector can detect a first reflected beam based on the first optical beam and can detect a second reflected beam based on the second optical beam. The processing portion can determine the presence of the object based on the first reflected beam and the second reflected beam. The indicator can generate an indicator signal based on the presence of the object.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. application Ser. No.13/291,668, filed Nov. 8, 2011, which claims priority to and the benefitof U.S. Provisional Application Ser. No. 61/411,261, filed Nov. 8, 2010,now expired, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to optical beam steering systems.

2. Description of the Related Art

Conventional methods for intruder detection include video monitoring,infrared detection and acoustic detection. These methods for intruderdetection are human intensive for screening out false alarms.

What is needed is a system and method for detecting, classifying,tracking and communicating information for intruders which requires lesshuman intervention for operation.

SUMMARY OF THE INVENTION

The present invention provides a system and method for an intrudernetwork system for detecting, classifying, tracking and communicatinginformation associated with an intruder.

In accordance with an aspect of the present invention, a device isprovided for detecting a presence of an object. The device includes anoptical phased array, a detector, a processing portion and an indicator.The optical phased array can transmit a first optical beam to a firstlocation at a first time and can transmit a second optical beam to asecond location at a second time. The detector can detect a firstreflected beam based on the first optical beam and can detect a secondreflected beam based on the second optical beam. The processing portioncan determine the presence of the object based on the first reflectedbeam and the second reflected beam. The indicator can generate anindicator signal based on the presence of the object.

Additional advantages and novel features of the invention are set forthin part in the description which follows, and in part will becomeapparent to those skilled in the art upon examination of the followingor may be learned by practice of the invention. The advantages of theinvention may be realized and attained by means of the instrumentalitiesand combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate at least one exemplary embodiment of thepresent invention and, taken together with the description, explain theprinciples of the invention. In the drawings:

FIG. 1 is an illustration for an example intruder network system, inaccordance with an aspect of the present invention;

FIG. 2 illustrates an example node as described with reference to FIG.1, in accordance with an aspect of the present invention;

FIG. 3 is a block diagram for example node as described with referenceto FIG. 1, in accordance with an aspect of the present invention;

FIG. 4 is an example illustration for the operational modes for theintruder network system as described with reference to FIG. 1, inaccordance with an aspect of the present invention;

FIG. 5 is an example illustration of a graph for the operation of nodesas described with reference to FIG. 1, in accordance with an aspect ofthe present invention;

FIG. 6 is an example illustration of a table for the characteristics anddesign parameter values for the system as described with reference toFIG. 1, in accordance with an aspect of the present invention;

FIG. 7 is an example illustration for a beam transmission chart for thesystem as described with reference to FIG. 1, in accordance with anaspect of the present invention;

FIG. 8 illustrates intruder detection for the example system asdescribed with reference to FIG. 1, in accordance with an aspect of thepresent invention;

FIG. 9 illustrates an example system as described with reference to FIG.1, in accordance with an aspect of the present invention; and

FIG. 10 illustrates an example method for detecting, classifying,tracking and communicating information associated with an intruder, inaccordance with an aspect of the present invention.

DETAILED DESCRIPTION

In accordance with aspects of the present invention, an intruder networksystem is presented for detecting, classifying and tracking an intrudervia lidar.

Lidar is an optical remote sensing technology that can measure thedistance to, or other properties of a target or an intruder byilluminating the target with light. Light is often generated usingpulses from a laser. Lidar may use ultraviolet, visible or near infraredlight in order to receive and process light reflected from surroundingobjects and terrain. Light is typically reflected via backscattering. Inan example embodiment, an optical phased array may include that whichdescribed in U.S. patent application Ser. No. 13/047,379, filed Mar. 14,2011, titled “System and Method for Using Planar Device to Generate andSteer Light Beam,” to Papadakis et al., the entire disclosure of whichis incorporated by reference herein.

Furthermore, intruder network system communicates information associatedwith intruder to other nodes and a control system in order to performfurther detection, classification, tracking and communication for theintruder by the other nodes and the control system.

Intruder network system provides a lidar sensor network using a flat,optical phase array laser aperture. The network of optical phase arraylidars provides automatic collaborative detection, tracking, classifyingand acquisition cueing. The network includes a plurality of nodes forperforming lidar processing. As a non-limiting example, a node of thesystem is configured with four optical phased arrays, each withapproximately 1 million radiating elements in a 1-cm² aperture enablingelectronic beam steering. Furthermore, the four arrays are mounted onfour sizes of a structural component associated with a node therebyproviding a 360 degree field of view. A plurality of nodes providesdetection, tracking, classifying and acquisition cueing over a largegeographical area.

Intruder network system provides a three-dimensional position of objectsusing a single sensor device. Furthermore, processing by system does notrequire correlation or estimation algorithms.

A plurality of nodes enables collaboration between the node devices forconditions of obstacle blockages and countermeasures such as lidarblinding.

Intruder network system may operate in daylight or nighttime conditions,as compared to some conventional systems which only operate in nighttimeconditions (e.g. passive infrared).

Aspects of the present invention will now be described in detail withreference to FIGS. 1-10.

FIG. 1 is an illustration for an example intruder network system 100, inaccordance with an aspect of the present invention.

Intruder network system 100 includes a node 102, a node 104 and a node106 and a control station 108.

Intruder network system 100 performs operations associated with intrudersearch, detection, classification, tracking and communicating. As anon-limiting example, intruder network system 100 may be used fordetecting, classifying and tracking a person trespassing on an entitiesproperty and for communicating information associated with a trespassingperson.

Nodes 102, 104 and 106 search for, detect, classify and track intrudersand communicate information associated with intruders. Furthermore,nodes 102, 104 and 106 search for, detect, classify and track intrudersand communicate information optically.

Control station 108 communications information bi-directionally with thenodes and presents information received and processed from nodes.

Node 102 communicates bi-directionally with node 104 via an opticalcommunication channel 110. Node 104 communicates bi-directionally withnode 106 via an optical communication channel 112. Node 104 communicatesbi-directionally with control station 108 via an optical communicationchannel 114. Node 106 communicates bi-directionally with control station108 via an optical communication channel 116.

In this example, node 102 is not able to communicate directly with node106 or control station 108 due to an obstruction 118 blocking theline-of-sight between node 106 and control station 108. Node 102 maycommunicate with node 106 and/or control station 108 indirectly viacommunication with node 104. Nodes 102, 104, 106 and/or control station108 may communicate bi-directionally with one another directly and/orindirectly.

Intruder network system 100 performs searches for, detects, classifies,tracks and communicates information associated with an intruder 120.

Node 102 transmits a lidar beam 122. Furthermore, node 102 receives andprocesses reflections of lidar beam 122. Node 104 transmits a lidar beam124. Furthermore, node 104 receives and processes reflections of lidarbeam 124. Node 106 transmits a lidar beam 126. Furthermore, node 106receives and processes reflections of lidar beam 126.

Nodes 102, 104 and 106 perform operations associated with intruders bytransmitting a plurality of optical beams and receiving and processingreflections of the transmitted optical beams. Furthermore, nodes 102,104 and 106 transmit, receive and process information from the othernodes and control station 108 associated with intruders.

As an example of typical operation, node 102 transmits lidar beam 122,node 104 transmits lidar beam 124 and node 106 transmits lidar beam 126.Node 102 receives and processes reflections of lidar beam 122. Node 104receives and processes reflections of lidar beam 124. Node 106 receivesand processes reflections of lidar beam 126. Node 106 detects intruder120. Node 106 classifies intruder 120. Node 106 tracks intruder 120.Node 106 communicates information associated with intruder 120 to node102, 104 and control station 108. If possible, node 102 searches for,classifies, tracks and communicates information for intruder 120. Ifpossible, node 104 searches for, classifies, tracks and communicatesinformation for intruder 120. Node 102 and node 104 communicateinformation associated with intruder 120 to node 106 and control station108. Control station 108 receives and processes information associatedwith intruder 120 and presents received and processed information forviewing. Furthermore, control station 108 may communicate an alarm or analert associated with received and processed information associated withintruder 120.

FIG. 1 is an illustration for an example intruder network system wherenodes transmit optical beams, receive and process reflected beams,search for, detect, classify, track and communicate informationassociated with an intruder or intruders.

In an example embodiment, node 102 receives and converts light energy toelectrical energy for storage, provides electrical power via storedelectrical energy, determines location information and time informationvia a GPS receiver, transmits a shaped beam, receives a reflected beam,processes reflected beam, communicates processed information to externalnodes, receives information from external nodes and processesinformation received from external nodes. This will be described ingreater detail with reference to FIG. 2.

FIG. 2 illustrates an example of node 102 as described with reference toFIG. 1, in accordance with an aspect of the present invention.

Node 102 includes an enclosure 202, an extendable mast 203 and anoptical array cube 204.

Enclosure 202 provides support for and containment of electronicdevices. As a non-limiting example, enclosure 202 may be configured in asquare shape with a side dimension of approximately 60 centimeters.

Extendable mast 203 provides height for electronic devices and as aconduit for communication cables between electronic equipment located inthe top of extendable mast 203 and electronic equipment located withinenclosure 202. Extendable mast 203 may be configured for a variety ofheights. As a non-limiting example, extendable mast 203 may beconfigured for approximately 100 centimeters.

Enclosure 202 includes a battery portion 206, a processor portion 208, aGPS receiver 212, a receiver portion 214, a transmitter portion 216 anda solar panel portion 218. In this example embodiment, receiver portion214 and transmitter portion 216 are distinct elements. In otherembodiments, receiver portion 214 and transmitter portion 216 may becombined as a unitary device. Further, in this example embodiment, GPSreceiver 212 and processor portion 208 are distinct elements. However,in other embodiments, GPS receiver 212 and processor portion 208 may becombined as a unitary device. Battery portion 206 receives, stores andprovides electrical power. Processor portion 208 provides execution ofoperational codes and storage/retrieval of information for controllingthe operation of node 102. GPS receiver 212 receives and processesinformation received via radio waves for determining geographic locationwith respect to the Earth. Furthermore, GPS receiver 212 provideslocation and time information for synchronization nodes. Receiverportion 214 may be a dual lidar/communication element, wherein it isoperable to receive information optically and by RF. Receiver portion214 may include a plurality of receiver elements, the combination ofwhich provides a combined ability to communicate with other nodes and toreceive optical information from a lidar sweep, as will be described ingreater detail later. In an example embodiment, receiver portion 214receives information optically associated with intruder detection,classification and tracking and receives information from externalentities. Transmitter portion 216 may be a dual lidar/communicationelement, wherein it is operable to transmit information optically and byRF. Transmitter portion 216 may include a plurality of transmitterelements, the combination of which provides a combined ability tocommunicate with other nodes and to transmit optical information from tocreate a lidar sweep, as will be described in greater detail later. Inan example embodiment, transmitter portion 216 transmits informationoptically for performing intruder detection, classification and trackingand for communicating with external entities. Solar panel portion 218receives light energy and converts the light energy to electricalenergy.

Extendable mast 203 includes an optical fiber portion 224 and anelectrical cable portion 226. Optical fiber portion 224 includes aplurality of optical fibers for bi-directional optical communication.Electrical cable portion 226 includes a plurality of electrical cablesfor bi-directional communication and for providing electrical power.Optical array cube 204 includes a plurality of optical phased arrayswith a sampling noted as an optical phased array 220 and a GPS antenna222.

Optical phased array 220 performs beam shaping for a lidar beam. GPSantenna 222 receives radio waves from external entities. A non-limitingexample of an external entity is a GPS satellite. Optical fiber portion224 provides a conduit for transmitting and receiving optical beams.Electrical cable portion 226 provides a conduit for transmitting andreceiving electrical signals and provides a conduit for transmission ofelectrical power.

Optical phased array 220 includes an optical layer portion 228 and anintegrated circuit layer portion 230. Optical layer portion 228 providestransmission, distribution and shaping for an optical beam. Integratedcircuit layer portion 230 provides control and configuration of opticallayer portion 228. Optical layer portion 228 includes an array aperture232 and an optical feed 234. Array aperture 232 provides steering for anoptical beam. Optical feed 234 provides a conduit for an optical beam.

Array aperture 232 includes an array of crossed optical waveguides witha sampling noted as an optical waveguide 236. An optical waveguide is aphysical structure for guiding electromagnetic waves in the opticalspectrum. The rows and columns associated with the array of crossedoptical waveguides are spaced pseudo-randomly in order to minimizecross-coupling while providing adequate array element density andside-lobe control. Optical waveguides are fabricated in an electro-optic(EO) material. As a non-limiting example, the EO material may bepolymethyl methacrylate.

Optical waveguides are controlled via a steering electrodes portion 237with a sampling noted as a steering electrode 238.

Steering electrodes control the phase of the light at the associatedintersections and as a result perform optical beam steering. For an N×Narray of optical waveguides, an associated 2N steering electrodes areprovided. The steering electrodes are located on the back side ofoptical layer portion 228 enabling control by integrated circuit layerportion 230.

Integrated circuit layer portion 230 receives and translates beamsteering directions received from processor portion 208 into informationfor controlling the steering electrodes. As a non-limiting example,information may be conveyed from integrated circuit layer portion 230 tosteering electrodes via a voltage.

A ground plane (not shown) is configured by placing of an L-shapedelectrode on top of optical layer portion 228 and over the steeringelectrodes. A plurality of intersections is formed at the location wherethe optical waveguides cross with a sampling noted as an intersection240.

Optical feed 234 includes a cascade of multimode-interface (MMI)splitters providing distribution of an optical beam. Optical waveguidesare fed along their lower edge by edge-coupled optical fibers traversingextendable mast 203 and terminating in enclosure 202. Optical fiberscarry optical power from transmitter portion 216 and to receiver portion214.

As a non-limiting example, polymethyl methacrylate yields an averagewaveguide period of 9 μm. Furthermore, as a non-limiting example, forN=1000, the 9 μm spacing yields a total array size of 9×9 mm.Furthermore, as a non-limiting example, the steering electrodes and MMIsplitters occupy approximately 5 mm of length for optical layer portion228 resulting in an area size for array aperture 232 of approximately15×15 mm.

The extendibility of extendable mast 203 enables obstacle clearance andsufficient range to the optical horizon.

In operation, solar panel portion 218 receives light energy (e.g. Sun)and converts the light energy to electrical energy. The generatedelectrical energy is transferred to and stored by battery portion 206.Battery portion 206 provides electrical power to electrical andelectronic devices associated with node 102. GPS receiver 212 receivesand processes positioning and time information by way of GPS satellites,GPS antenna 222 and electrical cable portion 226.

A laser portion 210 provides an optical light beam to optical phasedarray 220 via laser portion 210 and optical fiber portion 224. Processorportion 208 determines and communicates beam steering information tooptical phased array 220 via electrical cable portion 226. Integratedcircuit layer portion 230 receives and processes steering informationand communicates configuration information to steering electrodesportion 237. Steering electrodes configure beam shape for transmittedbeam.

Transmitted beam traverses external to node 102, impinges on externalobjects and is reflected back to node 102. Reflected beam is received byoptical phased array 220 and communicated to receiver portion 214 viaoptical fiber portion 224. Receiver portion 214 communicates receivedinformation to processor portion 208. Processor portion 208 receives andprocesses information for determining information associated withexternal objects. Processor portion 208 communicates processedinformation associated with external objects to external nodes viatransmitter portion 216, optical fiber portion 224 and optical phasedarray 220.

External nodes receive and process information. External nodescommunicate processed information to processor portion 208 by way ofoptical phased array 220, optical fiber portion 224 and receiver portion214. Processor portion 208 receives and processes information fromexternal nodes.

FIG. 3 is a more detailed block diagram for node 102 as described withreference to FIG. 1, in accordance with an aspect of the presentinvention.

Integrated circuit layer portion 230 receives information from processorportion 208 via a communication channel 302. Receiver portion 214receives information from optical layer portion 228 via an opticalcommunication channel 304. Optical layer portion 228 receivesinformation from transmitter portion 216 via an optical communicationchannel 306. Battery portion 206 receives electrical power from solarpanel portion 218 via a power conduit 308. Optical phased array 220receives electrical power from battery portion 206 via an electricalpower conduit 310. Processor portion 208 receives electrical power frombattery portion 206 via an electrical power conduit 312. GPS antenna 222receives information from external entities via a communication channel314. GPS receiver 212 receives information from GPS antenna 222 via acommunication channel 316. Steering electrodes portion 237 receivesinformation from integrated circuit layer portion 230 via acommunication channel 318. Optical layer portion 228 receivesinformation from steering electrodes portion 237 via a communicationchannel 320. Optical layer portion 228 communicates bi-directionallywith external entities and performs detection, classification andtracking via an optical communication channel 324.

Further, in some embodiments at least one of processor portion 208, GPSreceiver 212, receiver portion 214, transmitter portion 216, opticalphased array 220, optical layer portion 228, integrated circuit layerportion 230 and steering electrodes portion 237 may be implemented as acomputer having stored therein tangible computer-readable media forcarrying or having computer-executable instructions or data structuresstored thereon. Such tangible computer-readable media can be anyavailable media that can be accessed by a general purpose or specialpurpose computer. Non-limiting examples of tangible computer-readablemedia include physical storage and/or memory media such as RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium which can be used tocarry or store desired program code means in the form ofcomputer-executable instructions or data structures and which can beaccessed by a general purpose or special purpose computer. Wheninformation is transferred or provided over a network or anothercommunications connection (either hardwired, wireless, or a combinationof hardwired or wireless) to a computer, the computer properly views theconnection as a computer-readable medium. Thus, any such connection isproperly termed a tangible computer-readable medium. Combinations of theabove should also be included within the scope of tangiblecomputer-readable media.

In operation, solar panel portion 218 receives light energy (e.g. Sun)and converts the light energy to electrical energy. The generatedelectrical energy is transferred to and stored by battery portion 206via electrical power conduit 308. Battery portion 206 provideselectrical power to electrical and electronic devices associated withnode 102 including processor portion 208 via electrical power conduit312 and optical phased array 220 via electrical power conduit 310.

GPS receiver 212 receives and processes positioning and time informationby way of GPS satellites (not shown), communication channel 316, GPSantenna 222 and communication channel 314. Transmitter portion 216provides an optical light beam to optical layer portion 228 via opticalcommunication channel 306. Processor portion 208 determines andcommunicates beam steering information to integrated circuit layerportion 230 via communication channel 302. Integrated circuit layerportion 230 receives and processes steering information and communicatesconfiguration information to steering electrodes portion 237.

Steering electrodes configure beam shape for transmitted beam.Transmitted beam traverses external to node 102 via opticalcommunication channel 324, impinges on external objects and is reflectedback to node 102. Reflected beam is received by optical layer portion228 and is communicated to receiver portion 214 via opticalcommunication channel 304. Processor portion 208 receives reflected beaminformation via receiver portion 214. Processor portion 208 processesreceived information for determining information associated withexternal objects. Processor portion 208 communicates processedinformation associated with external objects to external nodes viatransmitter portion 216, optical communication channel 306 and opticallayer portion 228.

External nodes receive and process information. External nodescommunicate processed information to processor portion 208 by way ofoptical layer portion 228, optical communication channel 304 andreceiver portion 214. Processor portion 208 receives and processesinformation from external nodes.

FIG. 4 is an example illustration for the operational modes 400 forintruder network system 100 as described with reference to FIG. 1, inaccordance with an aspect of the present invention.

Operational modes 400 include a search mode 402, a classification mode404, a tracking mode 406, a communication mode 408 and a third-partyacquisition mode 410.

Intruder network system 100 executes a plurality of modes for operationincluding searching, classifying, tracing, communicating and third-partyacquiring.

For search mode 402, a node (e.g. node 102, 104 and/or 106 as describedwith reference to FIG. 1) transmits lidar beams and receives reflectedlidar beams in order to detect the presence of a potential intruder.

In search mode 402, lidar beams are swept through the monitoring area ina pseudorandom pattern. The lidar beams are configured in a pseudorandompattern in order to aid in defeating potential countermeasures. Thetransmitted lidar beams are reflected by external elements and receivedby the node. As an example, the node compares previous receivedreflected lidar beams with recently received lidar beams in order todetermine movement associated with an external element (e.g. person,intruder, vehicle, etc.). As a further example, a pattern of reflectedlidar beams received similar to previous lidar beams would indicate theabsence of a potential intruder and a pattern of reflected lidar beamsreceived dissimilar to previous lidar beams may indicate the presence ofa potential intruder.

For classification mode 404, a node, following detection of a potentialintruder, performs classification of the potential intruder. In theclassification mode 404, intruder network system 100 transmits lidarbeams with a fine pattern in order to get a high resolutionrepresentation of an intruder. The signature of the received intruder isthen compared to a database of stored signatures in order to find amatch for the intruder. For example, the intruder may be classified asan animal, human or vehicle.

In classification mode 404, the node compares the signature of thereceived reflected lidar beam with signatures of known intruder elements(e.g. person, truck, dog, cat, etc.) for determining a match. Node mayuse any known method for processing signatures for determining a match.Furthermore, the node may process the shape and/or size of the potentialintruder to determine interest in further processing for the potentialintruder.

For tracking mode 406, a node, following classification of a potentialintruder, tracks the movement of the potential intruder. Based uponprevious movements of the potential intruder estimates are generated forfuture movements of the potential intruder and processed for accuracyfollowing movement of the potential intruder.

In tracking mode 406, the node estimates future movements of thepotential intruder based upon previous movements of the potentialintruder. Furthermore, actual movements are compared to actual movementsfor determining accuracy of estimates. Estimates of future movements arerefined based upon comparisons of actual versus estimated movements.

For communication mode 408, a node, following completion for estimatingfuture movements of potential intruder, communicates informationassociated with the potential intruder to other nodes and the controlstation.

In communication mode 408, non-limiting examples of informationcommunicated to other nodes include velocity vector, acceleration,location, size, shape and estimated future velocity vector, accelerationand location.

For third-party acquisition mode 410, a node, following receipt ofinformation associated with a potential intruder, processes the receivedinformation in order to detect, classify and track the potentialintruder.

In third-party acquisition mode 410, a node receiving information fromanother node processes information to determine a configuration fordetecting, classifying and tracking a potential intruder. Furthermore,node uses processed information for performing search mode 402,classification mode 404, tracking mode 406 and communication mode 408.

A plurality of nodes aids in compensating for blockages associated withterrain or for mitigating potential countermeasures. As an example, apotential intruder may successfully blind a node, but other non-blindednodes may track the potential intruder.

A node may transmit lidar beams and receive reflected lidar beams fordetecting, classifying and tracking a potential intruder. The node mayadditionally transmit lidar beams and receive reflected lidar beams forcommunicating information associated with potential intruder to othernodes and to the control station with control station communicationinformation associated with potential intruder to other nodes. Further,other nodes may transmit lidar beams and receive reflected beams fordetecting, classifying and tracking a potential intruder. Still further,other nodes may transmit lidar beams and receive reflected lidar beamsfor communicating information associated with intruder to other nodesand to the control station. This will be described in greater detailwith additional reference to FIG. 5.

FIG. 5 is an example illustration of a graph 500 for the operation ofnodes as described with reference to FIG. 1, in accordance with anaspect of the present invention.

Graph 500 includes a y-axis 501 with units of meters and an x-axis 502with units of meters.

Node 104 (and node 106) transmits a plurality of lidar beams with asampling noted as a lidar beam 503 and a lidar beam 504. The beams maybe transmitted in any predetermined pattern. In some examples, the lidarbeams are transmitted in a pseudo-random pattern. The beam width oflidar beam 503 is noted as a beam width 506. As a non-limiting example,beam width 506 is 0.01°.

Intruder 120 with a location noted as a geographic location 510 and withdirection of movement noted as a velocity vector 512 is not detected ata location noted as geographic location 510, as the distance betweenintruder 120 and node 104 is too large a distance for detection.

At a location for intruder 120 noted as a geographic location 514, node104 transmits a plurality of lidar beams with a sampling noted as alidar beam 513. Furthermore, transmitted lidar beams may be reflected byobjects. Furthermore, a lidar beam 516 is reflected version of lidarbeam 513 and noted as a reflected lidar beam 518. As a non-limitingexample, geographic location 514 for detecting intruder 120 may berealized nominally at 0.4 kilometers in an unobstructed view.

Node 104 receives reflected lidar beam 518 and other associatedreflected lidar beams, processes reflected beams and detects movementassociated with intruder 120.

As a result of detecting intruder 120, node 104 transmits a contiguouspattern of lidar beams in the direction of intruder 120. Node 104receives reflections from continuous pattern of lidar beams transmittedin direction of intruder 120 and performs a classification of intruder120. As a non-limiting example, node 104 may classify intruder 120 ashuman, dog, cat, horse and automobile.

At a location for intruder 120 noted as a geographic location 520, node104 tracks the location and movement of intruder 120 by estimatingfuture information for intruder 120 followed by comparing estimatedinformation with actually received information.

At a location for intruder 120 noted as a geographic location 522, node104 communicates to information associated with intruder 120 to controlstation 108 via a lidar beam 524. Communication may be transmitted bynode 104 and received by control station 108 during a periodiccommunication timeslot. Non-limiting examples of informationcommunicated include node identification, node location, intrudercoordinates and track state vector for correlation with the returnsassociated with other nodes.

At a location for intruder 120 noted as a geographic location 526,control station 108 communicates information associated with intruder120 to node 106 via a lidar beam 528.

At a location for intruder 120 noted as a geographic location 530, node106 receives information associated with intruder 120 from node 104 viaa lidar beam 532.

Node 104 continues to periodically communicate updated informationassociated with intruder 120 to control station 108 and node 106.Control station 108 continues to periodically communicate updateinformation associated with intruder 120 to node 106.

Node 106 monitors received information associated with intruder 120 andwhen intruder 120 is located at a geographic location 534 such that node106 determines intruder 120 is within sufficient range for detection,node 106 transmits a lidar beam 536.

Node 106 continues attempts track intruder 120 until node 106successfully detects intruder 120 or until node 106 experiences atimeout condition and ceases detection efforts for intruder 120. Thetimeout condition may be set at a predetermined time. As a non-limitingexample, the timeout value for node 106 ceasing to attempt to detectintruder 120 is 10 minutes.

At a location for intruder 120 noted as a geographic location 538, node106 transmits a lidar beam 540 that is reflected by intruder 120 asnoted by a reflected lidar beam 542. Node 106 is able to detect,classify and track intruder 120 as a result of receiving reflected lidarbeam 542 and successive reflected lidar beams.

At a location for intruder 120 noted as a geographic location 544, node106 communicates information associated with intruder 120 to controlstation 108 via a lidar beam 546 and to node 104 via a lidar beam 548.

In an example embodiment a system in accordance with aspects of thepresent invention may perform intruder detection, classification andtracking during 0.9 of a second and perform communication activitiesduring the remaining 0.1 of a second. The characteristics and designparameter values for such an example system will now be furtherdescribed with reference to FIG. 6.

FIG. 6 is an example illustration of a table 600 for the characteristicsand design parameter values for the system as described with referenceto FIG. 1, in accordance with an aspect of the present invention.

Table 600 includes a characteristics table portion 602 and a designparameter table portion 604.

Characteristics table portion 602 provides operational informationassociated with the system as described with reference to FIG. 1. Designparameter table portion 604 provides design parameter values associatedwith the design and fabrication of the system as described with respectto FIG. 1.

A row 606 notes a detection range of 400 meters with a 10% reflexivityfor a human moving about the pace of a walk. A value for 10% reflexivityrepresents the target impinged by a lidar beam reflecting 10% of thereceived lidar beam. A row 608 notes a Free Space Optical (FSO) range of1 kilometer. A value of 1 kilometer indicates the operational range ofthe system enclosed in a vacuum. A row 610 notes volume search coverageof 360 degrees with an azimuth of −0.1° to +0.4° in elevation. Systemmay search in 360 degrees and with an azimuth of −0.1° to +0.4° inelevation. A row 612 notes volume search coverage period as less than 1second for 2% of volume and fifty seconds for the plurality of beampositions. System may search 2% of the search volume in less than 1second and may search in the aggregate of beam positions in 50 secondsor less. A row 614 notes a transition to track of less than fiveseconds. System is able to track a potential intruder in less than 5seconds from first detection of potential intruder. A row 616 notes atrack update rate of 1 Hz. System may update tracking information withother nodes and control system at a rate of 1 Hz.

A row 618 notes an energy per pulse of 1.6 micro Joule. The amount ofenergy transmitted in a pulse may be configured for 1.6 micro Joule. Arow 620 notes a pulse width of four nanoseconds. The pulse width of atransmitted beam may be configured for four nanoseconds. A row 622 notesa pulse repetition interval of 25 microseconds. System may transmitpulses at a rate of once every 25 microseconds. A row 624 notes a pulseintegration of 4 non-coherent pulses. A row 626 notes a target dwelltime of 100 microseconds. A row 628 notes a range resolution of 0.6meters. A row 630 notes a wavelength of 1550 nanometers. System maytransmit and receive lidar beams with a wavelength of 1550 nanometers. Arow 632 notes a F-number of 3. The F-number of for an optical lensrepresents the ratio of the focal length to the diameter of its clearaperture. A row 634 notes a beam width of 0.01°. System may transmit abeam with an angular width of 0.01°. A row 636 notes a pass band ofelastic channel of 0.1 nanometer. A row 638 notes a quantum efficiencyof 0.2. Quantum efficiency represents the percentage of photons receivedby a photo-reactive surface producing an electron-hole pair. A row 640notes a receiver electronic bandwidth of twenty MHz. Electronicsassociated with system for transmitting/receiving an optical signal mayhave a bandwidth of twenty MHz. A row 642 notes a pre-amplifier currentnoise density of 2.12 e-12 (A/HZ)^(1/2). A row 644 notes an amplifiernoise factor of 1. Amplifier noise factor represents the amount ofexcess noise added to a signal by an amplifier. A row 646 notes anon-multiplied dark current of 0.2 e nA. A row 648 notes a multiplieddark current of 0.2 e nA. A row 650 notes a detector noise factor oftwenty. Detector noise factor represents the amount of excess noiseadded to a signal by a detector. A row 652 notes a detector current gainof 100. The ratio of the input signal to the output signal may beconfigured as 100. A row 654 notes a target area associated with aperson as 11148 cm² (0.7×1.9 m). A row 656 notes a target reflectance of0.1. Target reflectance indicates the amount of a beam is reflected andin this case indicates 10% of a beam received by a target is reflected.A row 658 notes an array loss of 6 dB.

At the powers and pulse widths as noted in design parameter tableportion 604, care needs to be taken in order to avoid damaging theoptical components due to the small mode-field area (MFA) of thewaveguides. The fibers connecting the lasers to the array faces have aMFA of about 80 μm² yielding a fluence of about 2 J/cm². The arrayitself is a polymeric Electro-Optic (EO) material, with the input powerdivided equally among the plurality of the waveguides. Furthermore, thecascading splitter network that divides power is also polymeric.Coupling directly into a single polymer waveguide on each surface wouldresult in a fluence of about 40 J/cm², far in excess of the polymer'sapproximate 1-J/cm² damage threshold. To compensate for this issue, theoptical layer is composed of multiple materials, with silica waveguidesused for the first two stages of the cascading (Multi-Mode Interference)MMI splitter network (to go from 1 to 100 waveguides per side of thearray) and polymer used for the last stage of the cascade (to go from100 to 1000 waveguides) and the array itself.

The patterned silica waveguides are coupled directly to the polymerwaveguides via lithography. Waveguides are fabricated of the samesubstrate material.

The communication mode for the system requires much less power than thelidar modes, therefore the lidar nodes dominate the power requirementsfor the system. Whether a solar array/battery configuration as describedwith reference to FIG. 2 or a system supplied by grid electrical powerdepends upon the efficiency of the lidar transmitters selected.

Each array face has its own lidar transmitter and receiver, totalingfour per node, so for lidar nodes each array operates in parallel andindependently. Furthermore, a 250 mW fiber communicationstransmitter/receiver may be switched into the arrays, one at a time,according to the time window reserved for FSO communications.

Since lidar and communications are at 1550-nm wavelength, ranges may beaffected by significant dust and fog. For example, at a fog visibilityof 100-m visibility, the preceding node range would be reduced fromnearly 400 m to 56 m at 1550-nm wavelength. In weather-based impairmentis perceived by system, system may power down optical system and switchto operation using alternative methods.

Arrays are connected to independent laser sources and receivers and thefour arrays may transmit and receive information in parallel. Systemseeks to search the volume and update tracking information every second.

For each array that scans 90° in azimuth and from −0.1° to +0.4° inelevation per second, 450,000 contiguous beams are transmitted. With 100microseconds per beam dwell, it takes 45 seconds per volume scan for thevarious beam positions. In contrast, 10,000 dwells are achieved persecond at 100 microseconds dwell intervals. To accomplish the volumeupdate with few beams (10,000 versus 450,000), it is recognized that thecross-beam coverage at 500-m range is 8.7 cm. Therefore, for detectionof objects of interest that are, for example, 0.5 m wide and 2 m tall,the system may be configured to transmit every fifth contiguous beamposition in azimuth and every tenth beam position in elevation. In thismanner, every transmitted azimuth beam position center is separated byapproximately 44 cm, and each transmitted elevation beam position isseparated by approximately 87 cm. Thus, a human, larger animal, orvehicle is covered by one of the distributed lidar beams. In order tofurther hedge against a potential intruder slipping through the volumeof lidar beams, the system changes pulses every second, so that theplurality of beam position shave been covered in 45 seconds with 10,000available beams. By using 2% of the 450,000 beam positions, 9000 persecond are needed per array to adequately search the volume per second,with the plurality of the beam positions covered every 50 seconds.

For detection, a three-dimensional clutter map, storing informationassociated with a received echo or not received echo at each pulseresolution cell for each of the 450,000 beam positions (only partlyupdated per second, but fully updated every 50 seconds). A clutter mapis used as opposed to Doppler detection in order to enable use ofoff-the-shelf, low-cost lidar systems. Even for expected detections of400 m, detections may occur and for higher reflectivity objects out to 1kilometer. Furthermore, 1500 range resolution cells result per beamposition and 450,000 beam positions per array and with four arraysresults in a clutter volume of 2.7 gigabytes. The memory of 2% of thememory cells is updated every second, with cells updated each 50seconds. The detection algorithm determines physical motion by detectingchanges in a number of contiguous cells over time. Once it is determineda grouping of cells of comparable range and angle have change, the nodeis directed to scan a 20×20 beam pattern for every other beam positionover a 40×40 beam position area at that location as a priority interruptfrom the search pattern. This would cover a 3.5×3.5-m cross-range at 500m. If a significant portion of beam positions in this pattern receivesechoes at about the same ranges, a detection is declared. During eachsuccessive second, a track-update beam is scheduled at the center of thedetected beam pattern. Updates are entered into a track filter for eachtrack. If a track update return is not received over several seconds,another 20×20 beam acquisition is attempted. Therefore, of the 9000array dwells identified for each second, a multiple of 400 beams areinterrupted for each transition to track.

When a detection has been determined and tracking initiate, the nodetransmits the track state data as well as the estimated cross-sectionalarea of the intruder to the nearby nodes and to the control system. Atthe control system, the cross-sectional area is an indication ofintruder size and the tracking velocity indicates whether the intruderis potentially a vehicle traveling faster than a human. The informationcommunicated by a node is used by other nodes to cue an acquisition ofthe intruding object. This further verifies the detection and maintainstracking by other nodes in case the intruder passes out-of-sight orbehind obstacles with respect to the initial detection node. Due toGlobal Positioning System (GPS) uncertainty larger than the lidar beamand range accuracy, a receiving node may provide special monitoring of abeam patter covering the indicated location out to 5 to 10 meters oneach side in azimuth depending upon ambiguity calculations for thetarget and lidar geometry. In this special region, the clutter mapdetector is set to high detection and corresponding false alarmprobabilities in that area based on the acquisition message of aneighboring node. If the cued node makes a detection and transitions toa tracking process, it sends a message to neighboring nodes indicating adetection associated with the tracking state received by the cueing nodethat transmitted the tracking state. In this way, a basic swarmingbehavior is performed.

Since 10,000 dwells are available and 9,000 are used for detection,acquisition and tracking, 1000 dwells or 0.1 second per second isavailable for each array in order to communicate tracking andidentification data via the FSO channel. Whereas four lidar sources andreceivers, one for each array, one communication source for receipt isshared among the four arrays, with an array transmitting data in thedirection of other nodes. At 100 Mbps, a total of 10 Mb may betransmitted and/or received at a time. Using a simple error detectionand correction code of 12 bits per information bit, 0.8 Mb of data maybe communicated per second per node. Using 32 bits per word, then 26,000words per second may be sent or received from each node in the allocated0.1-second window each second.

The system does not require mechanical gimbals since the optical phasedarrays provide electronic beam pointing. At 1 kilometer of communicationrange between the neighboring nodes, it is sufficient that thetransmitter aperture gain be used but significant receive aperture gainis not needed. Due to the short communication distances and low datarages, atmospheric turbulence compensation and advanced automatic gaincontrol features are not needed.

A variety of network operational schemes may be devised for directivetransmission and reception using combinations of time-divisionmultiplexing (TDM) and wavelength-division multiplexing (WDM). As anexample, for network initiation, each node is initially set foromni-directional reception in which the arrays are set to an approximate0-dB gain (+1-3 dB). The control station transmits interrogation beamsat low data rates, with an indication of GPS time, location and a noderesponsive time window. The control station beam sweeps in a 360°azimuth “interrogation” pattern. As individual nodes receive theinterrogation, typically at different time frames, the nodes respondwith high gain transmit beams pointing toward the control station withinthe indicated time window, during which time the monitor arrays are setto omni-directional gain. A number of potential interrogation responseWDM channels are available from which each node is randomly assigned fortransmission of a response. The control station can receive multipleresponses at different WDM channels simultaneously for channel decodingduring the response time windows. Alternatively, the nodes could use thesame wavelength and, using GPS time synchronization, a TDM structure maybe implemented in which each node takes turns communicating with thecontrol station. FSO communications includes appropriate FSO errordetection and correction coding and commercially available dataencryption. The control station transmits interrogation beams followedby a listening time window for several cycles to ensure nodes haveresponded. The control station then communicates to each node a table oflocations for the reporting nodes associated with the network. Followingthis, communications between nodes and control system are directional.

During each second using GPS time synchronization and positionalignment, nodes perform surveillance, tracking, cued acquisition andintruder classification functions for the first 0.9 of a second andprovide the remaining 0.1 second for transmission and reception ofneighboring node acquisition cue tracking updates. During the 0.1-secondwindow, nodes configure their arrays to receive from their nearestneighbors in anticipation of a potential acquisition cue message.Furthermore, nodes with tracking cue data transmit the associatedinformation to their neighbors via their directive apertures.Furthermore, detections, tracking updates and identification images maybe communicated to the control station during the 0.1-second window. Thecontrol station may also transmit commands to nodes during the0.1-second window.

System may be applied to vehicle collision avoidance and control,short-range inter-vehicle communication and surveillance andcommunication inside of buildings.

In an example embodiment, successive sweeps of transmitted and reflectedbeams are used for determining the presence of a moving object. Thiswill be further described with reference to FIG. 7.

FIG. 7 is an example illustration for a beam transmission chart 700 forthe system as described with reference to FIG. 1, in accordance with anaspect of the present invention.

Beam transmission chart 700 includes a plurality of dotted first lidarbeams with a sampling noted as a dotted first lidar beam 702 and aplurality of dashed second lidar beams with a sampling noted as a dashedsecond lidar beam 704.

Dotted first lidar beam 702 indicates the transmission of a lidar beamand the reception of an associated echo if an echo occurs. The pluralityof dotted first lidar beams represents a pattern of lidar beamstransmitted in on second. The plurality of dashed second lidar beamsrepresents a pattern of lidar beams transmitted in the second followingthe transmission of the dotted first lidar beams. For example, a dottedfirst lidar beam 706 follows the transmission of dotted first lidar beam702. Furthermore, a dotted first lidar beam 708 represents the last beamof the plurality of dotted first lidar beams transmitted. Furthermore,dashed second lidar beam 704 follows transmission of dotted first lidarbeam 708.

The distance between the dotted first lidar beams and the associateddashed second lidar beams is noted as a distance 710. As a non-limitingexample distance 710 may be configured for 15.2 cm. The distance betweensuccessive dotted first lidar beams is noted as a distance 712. As anon-limiting example, distance 712 may be configured as 43.2 cm. Thedistance in height between one row of dotted first lidar beams and afollowing row of dotted first lidar beams is noted as a distance 714. Asa non-limiting example, distance 714 may be configured as 86.4 cm. Thediameter of a dotted first lidar beam is noted as a diameter 716. As anon-limiting example, diameter 716 may be configured as 7.9 cm.

The transmitted and reflected beams are used for detecting movingobjects as noted by intruder 120 and a vehicle 718. Comparisons betweenthe sweeps of transmitted and reflected beams are performed fordetermining the movement of an object. For example, a plurality of beamsreflected in one sweep of beams and a similar shaped reflection in asuccession of following sweeps but in a different location may indicatedthe presence and movement of an object.

In an example embodiment a system in accordance with the presentinvention detects an intruder due to movement and change in distancebetween the intruder and node between sweeps of transmitted lidar beams.This will be further described with reference to FIG. 8.

FIG. 8 illustrates intruder detection for the example system asdescribed with reference to FIG. 1, in accordance with an aspect of thepresent invention.

Four sweeps of lidar beam transmissions are presented with a first sweepof beam transmissions noted as a beam transmissions portion 802, asecond sweep of beam transmissions noted as a beam transmissions portion804, a third sweep of beam transmissions noted as a beam transmissionsportion 806 and a beam transmissions noted as a beam transmissionportion 808.

Beam transmissions portion 802 is transmitted first, followed by beamtransmissions portion 804, followed by beam transmissions portion 806and beam transmission portion 808.

The distance between a rock 810 and node 104 is noted as a distance 812.The location of rock 810 as observed by node 104 and the distanceobserved between rock 812 and node 104 does not change between sweeps oftransmitted lidar beams. Therefore, node 104 does not detect rock 810 asan intruder.

The distance between a tree 814 and node 104 is noted as a distance 816.The location of tree 814 may change between sweeps of transmitted lidarbeams due to wind; however, the distance does not change between sweepsof transmitted lidar beams. Therefore, node 104 does not detect tree 814as an intruder.

The location of intruder 120 is observed as changed by node 104 betweensweeps of transmitted lidar beams. Furthermore, the distance betweenintruder 120 and node 104 as noted by a distance 818 is observed asdifferent between the sweeps of transmitted lidar beams. For example,the location of intruder 120 as observed by beam transmissions portion802 is observed as different from the location of intruder as observedby beam transmissions portion 804. Furthermore, the distance betweenintruder 120 and node 104 is observed as being different between beamtransmissions portion 802 and beam transmissions portion 804. As aresult of detecting a different location and movement in the directionof node 104, intruder 120 is noted as an intruder.

Following detection as an intruder, node 104 performs classification andtracking for intruder 120. Furthermore, node 104 communicatesinformation associated with intruder 120 to other nodes and the controlstation. Furthermore, other nodes and control station may performdetection, classification, tracking and communication for intruder 120.

In an example embodiment, a system in accordance with aspects of thepresent invention transmits lidar beams, lidar beams are reflected fromexternal entities, reflected beams are detected and received to performintruder detection, classification and tracking. Information associatedwith intruder detection, classification and tracking may be presentedfor viewing and communicated externally to other nodes and the controlsystem. This will be further described with reference to FIG. 9.

FIG. 9 illustrates an example system as described with reference to FIG.1, in accordance with an aspect of the present invention.

Intruder network system 100 includes processor portion 208, an indicatorportion 902, an optical phased array portion 904 and a detector portion906. In this example, processor portion 208, indicator portion 902,optical phased array portion 904 and detector portion 906 are distinctelements. In some embodiments, at least two of processor portion 208,indicator portion 902, optical phased array portion 904 and detectorportion 906 may be combined as a unitary device.

Further, in some embodiments at least one of processor portion 208,indicator portion 902, optical phased array portion 904 and detectorportion 906 may be implemented as a computer having stored thereintangible computer-readable media for carrying or havingcomputer-executable instructions or data structures stored thereon.

Indicator portion 902 presents information associated with intruders.For example, indicator portion 902 may present location, size, movementand classification for an intruder. Optical phased array portion 904performs beam shaping for a lidar beam. Detector portion 906 receivesoptical information transmitted by optical phased array portion 904 andreflected by external entities and receives optical informationcommunicated from other nodes and the control station. Detector portion906 converts optical communicated information to electrical communicatedinformation.

Processor portion 208 includes receiver portion 214, transmitter portion216, a detector portion 908, a classifier portion 910, a tracker portion912 and a communication portion 914.

Detector portion 908 performs detection of intruders. For example,detector portion 908 may detect the presence of an animal, human or avehicle. Classifier portion 910 performs classification of intruders.For example, an intruder may be classified by classifier portion 910 asanimal, human or vehicle. Tracker portion 912 tracks the location andmovement of an intruder. For example, tracking portion may track that anintruder is 100 meters from a node and is traveling toward the node at20 kilometers per hour. Communication portion 914 communicatesinformation associated with detector portion 908, classifier portion 910and tracker portion 912 to external entities.

Detector portion 906 receives optical information via opticalcommunication channel 324. Receiver portion 214 receives informationfrom detector portion 906 via a communication channel 918. Detectorportion 908 receives information from receiver portion 214 via acommunication channel 920. Classifier portion 910 receives informationfrom receiver portion 214 via communication channel 920. Tracker portion912 receives information from receiver portion 214 via communicationchannel 920. Indicator portion 902 receives information from detectorportion 908 via a communication channel 922. Indicator portion 902receives information from classifier portion 910 via a communicationchannel 924.

Indicator portion 902 receives information from tracker portion 912 viaa communication channel 926. Communication portion 914 receivesinformation from detector portion 908 via communication channel 922.Communication portion 914 receives information from classifier portion910 via communication channel 924. Communication portion 914 receivesinformation from tracker portion 912 via communication channel 926.Transmitter portion 216 receives information from communication portion914 via a communication channel 928. Optical phased array portion 904receives information from transmitter portion 216 via a communicationchannel 930. Optical phased array portion 904 transmits information viaoptical communication channel 324.

In operation, processor portion 208 via way of transmitter portion 216and optical phased array portion 904 transmit lidar beams via opticalcommunication channel 324. Transmitted beams are received by externalentities and reflected back to detector portion 906 via opticalcommunication channel 324. Detector portion 906 converts received lidarbeams to electrical information and communicates information to receiverportion 214.

Receiver portion 214 provides received information to detector portion908, classifier portion 910 and tracker portion 912. Detector portion908 receives information from receiver portion 214 and performsdetection of intruder or intruders. Classifier portion 910 receivesinformation from receiver portion 214 and performs classification of anintruder or intruders. Tracker portion 912 receives information fromreceiver portion 214 and performs tracking of intruder or intruders.

Indicator portion 902 receives information from detector portion 908,classifier portion 910 and tracker portion 912 and presents informationbased upon the results received from detector portion 908, classifierportion 910 and tracker portion 912. For example, if detector portion908 indicates detection of an intruder, indicator portion 902 mayindicated the presence of an intruder and if classifier portion 910determines an intruder is a vehicle, then indicator portion 902indicates the respective intruder as a vehicle, and if tracker portion912 determines velocity of the intruder is 20 kilometers per hour, thenindicator portion 902 indicates the velocity of the intruder is 20kilometers per hour.

Communication portion 914 receives information from detector portion908, classifier portion 910 and tracker portion 912 and communicatesinformation based upon the results received from detector portion 908,classifier portion 910 and tracker portion 912. Furthermore,communication portion 914 communicates information to external entitiesvia transmitter portion 216, optical phased array portion 904 andoptical communication channel 324. For example, if detector portion 908indicates detection of an intruder, communication portion 914 maycommunicate the presence of an intruder and if classifier portion 910determines an intruder is a vehicle, then communication portion 914communicates the respective intruder as a vehicle, and if trackerportion 912 determines velocity of the intruder is 20 kilometers perhour, then communication portion 914 communicates the velocity of theintruder is 20 kilometers per hour.

FIG. 10 illustrates an example method 1000 for detecting, classifying,tracking and communicating information associated with an intruder, inaccordance with an aspect of the present invention.

Method 1000 starts (S1002) with a node (e.g. node 102) detectinggeographic location via GPS (S1004). For example, as described withreference to FIG. 3, processor portion 208 receives location informationvia communication channel 314, GPS antenna 222 and GPS receiver 212. Asa non-limiting example, a node determines the time of day is 8:30 A.MEastern Standard Time (EST).

Returning to FIG. 10, the node then transmits lidar beams (S1006). Forexample, as described with reference to FIG. 3 and FIG. 7, processorportion 208 transmits sweeps of beams via transmitter portion 216,optical layer portion 228 and optical communication channel 324. As anon-limiting example, a node transmits a plurality of sweeps of lidarbeams in 360° about the location of the node.

Returning to FIG. 10, the node then receives reflected lidar beams(S1008). For example, as described with reference to FIG. 5, a reflectedversion of lidar beam 513 is reflected as reflected lidar beam 518. As anon-limiting example, lidar beams are transmitted and reflected by anintruder moving towards the node.

Returning to FIG. 10, the node then processes reflected lidar beams(S1010). For example, as described with reference to FIG. 6, the nodecreates and processes information associated with a three-dimensionalclutter map. As a non-limiting example, a node transmits a first sweepof lidar beams, stores the reflected lidar beam information in firstthree-dimensional clutter map, transmits a second sweep of lidar beams,stores the reflected beam information in a second three-dimensionalclutter map, then compares the two clutter maps to determine if anintruder has been detected.

Returning to FIG. 10, the node then detects intruder (S1012). Forexample, after comparing the three-dimensional clutter maps, the nodedetermines it has detected an intruder. As a non-limiting example, thereflected and processed lidar beams indicated an intruder has beendetected.

Then the node classifies the detected intruder (S1014). For example, thenode compares signature information received for intruder and comparessignature to know signatures for determining the class associated withthe intruder. For example, the node may classify the intruder as ananimal, human or vehicle.

Then the node tracks the intruder (S1016). For example, the nodeprocesses received information for intruder to determine informationassociated with intruder. Non-limiting examples of informationdetermined include velocity, location and size. As a non-limitingexample, node determines intruder is a vehicle traveling at 20kilometers per hours in the direction of the node.

Then the node communicates information associated with the intruder toother nodes and the control system (S1018). For example, as describedwith reference to FIG. 5, the node initially detecting intrudercommunicates information associated with intruder to other nodes and tothe control system. As a non-limiting example, node communicates thelocation of the intruder to the other nodes and the control system andcommunicates the intruder is a vehicle traveling toward the node at 20kilometers per hour.

Returning to FIG. 10, then the other nodes and the control systemdetect, classify, track and communication information associated withintruder (S1020). For example, as described with reference to FIG. 5,the other nodes and the control system perform processing associatedwith the intruder. As a non-limiting example, the control systemdetects, classifies and tracks intruder and communicates informationassociated with intruder to other nodes.

Returning to FIG. 10, execution of method 1000 terminates (S1022).

An intruder network system has been presented for detecting, classifyingand tracking an intruder via lidar. System includes a plurality of nodestransmitting lidar, receiving reflected lidar and processing reflectedlidar. Furthermore, a node may communicate information associated with apotential intruder to other nodes via lidar. During the detectionportion, lidar beams are transmitted in a sparse pattern enablingsearching for an intruder over a particular volume of interest. Duringclassifying and tracking portions, lidar beams are transmitted in atight pattern over a small volume of interest where detection for anintruder was recognized. A node may communication information to othernodes via lidar by focusing and transmitting beams in the direction ofother neighboring nodes.

The foregoing description of various exemplary embodiments of theinvention have been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and many modifications andvariations are possible in light of the above. The example embodiments,as described above, were chosen and described in order to best explainthe principles of the invention and its practical application to therebyenable others of ordinary skill in the art to practice the invention invarious embodiments and with various modifications as are suited to theparticular use contemplated. The scope of the invention is defined bythe following claims.

What is claimed is:
 1. A method of monitoring an area, said methodcomprising: searching a first area via an optical phased array at afirst time; deriving, via a processing portion, a first signal based onsaid searching the first area via the optical phased array at the firsttime; searching the first area via the optical phased array at a secondtime; deriving, via the processing portion, a second signal based onsaid searching the first area via the optical phased array at the secondtime; and detecting, via the processing portion, an object within thefirst area based on the first signal and the second signal.
 2. Themethod of claim 1, further comprising searching, via the optical phasedarray, a second area including the object, the second area being smallerthan the first area.
 3. The method of claim 2, further comprisingderiving, via the processing portion, a third signal based on saidsearching, via the optical phased array, the second area including theobject.
 4. The method of claim 3, further comprising classifying theobject based on a priori information and the third signal.
 5. The methodof claim 4, further comprising transmitting, via a transmitter, objectinformation based on said classifying the object based on a prioriinformation and the third signal.
 6. The method of claim 5, furthercomprising tracking, via the optical phased array, movement of theobject.
 7. The method of claim 6, further comprising transmitting, viathe transmitter, object movement information based on said tracking, viathe optical phased array, movement of the object.
 8. The method of claim7, further comprising: receiving, via a receiver, the object movementinformation from the transmitter; deriving, via a second processingportion, a third area to search at a fourth time; and searching thirdarea via a second optical phased array at the fourth time.
 9. The methodof claim 3, further comprising tracking, via the optical phased array,movement of the object.
 10. The method of claim 9, further comprisingtransmitting, via a transmitter, object movement information based onsaid tracking, via the optical phased array, movement of the object. 11.The method of claim 10, further comprising: receiving, via a receiver,the object movement information from the transmitter; deriving, via asecond processing portion, a third area to search at a fourth time; andsearching third area via a second optical phased array at the fourthtime.